Python os.ftruncate() Method

Python File(文件) 方法 Python OS File/Directory Methods

Overview

os.ftruncate() truncates the file corresponding to the file descriptor fd; it cannot exceed the file size.

Available on Unix and Windows.

Syntax

ftruncate()The method syntax is as follows:

os.ftruncate(fd, length)

Parameters

fdfd -- The file descriptor.
lengthsize -- The file size to truncate.

Return Value

This method has no return value.

Example

The following example demonstrates the use of the ftruncate() method:

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import os, sys

# 打开文件
fd = os.open( "foo.txt", os.O_RDWR|os.O_CREAT )

# 写入字符串
os.write(fd, "This is test - This is test")

# 使用 ftruncate() 方法
os.ftruncate(fd, 10)

# 读取内容
os.lseek(fd, 0, 0)
str = os.read(fd, 100)
print "读取的字符串是 : ", str

# 关闭文件
os.close( fd)

print "关闭文件成功!!"

The output of the above program is:

读取的字符串是 :  This is te
关闭文件成功!!